CRUD

CRUD stands for Create, Read, Update, and Delete. These are the basic operations performed on database resources.

In an API, CRUD operations are commonly used to manage resources such as users, products, orders, or posts.

Code

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class User(BaseModel):
    name: str
    email: str
    age: int


users = []


@app.post("/users")
def create_user(user: User):
    users.append(user)
    return user


@app.get("/users")
def get_users():
    return users


@app.put("/users/{user_id}")
def update_user(user_id: int, user: User):
    users[user_id] = user
    return user


@app.delete("/users/{user_id}")
def delete_user(user_id: int):
    users.pop(user_id)

    return {
        "message": "User deleted"
    }

Understanding the Code

Create

The POST endpoint is used to create a new user:

@app.post("/users")
def create_user(user: User):
    users.append(user)
    return user

The new user is added to the users list.

Read

The GET endpoint is used to retrieve users:

@app.get("/users")
def get_users():
    return users

It returns the users currently stored in the list.

Update

The PUT endpoint is used to update an existing user:

@app.put("/users/{user_id}")
def update_user(user_id: int, user: User):
    users[user_id] = user
    return user

The user_id identifies which user should be updated.

Delete

The DELETE endpoint removes a user:

@app.delete("/users/{user_id}")
def delete_user(user_id: int):
    users.pop(user_id)

    return {
        "message": "User deleted"
    }

The user_id identifies which user should be removed.

CRUD Operations

The four basic CRUD operations are:

Operation	HTTP Method	Endpoint
Create	POST	/users
Read	GET	/users
Update	PUT	/users/{id}
Delete	DELETE	/users/{id}

Summary

CRUD provides the basic operations required to manage resources:

POST   /users          → Create
GET    /users          → Read
PUT    /users/{id}     → Update
DELETE /users/{id}     → Delete

In this example, the data is stored in a Python list. In a real FastAPI application, these operations would typically work with a database.